Aperture & Depth of Field

Even wonder how those photographer shot those blurry background but sharp object photo, or some call it the BOKEH photo?

Actually, those background blur effect is actually cause by the Depth of Field of the camera. In short, a shallow DOF will cause the background became blurry and a deep DOF will show the background clearly.

The DOF is directly related to the Aperture:

BIGGER Aperture size (F number smaller) –> Shallow DOF (Blurry background)

SMALLER Aperture size (F number bigger) –> Deep DOF (Clear background)

Another factor that affect DOF is the focal length (aka the zoom):

LONGER Focal length (Higher Zoom) –> Shallow DOF (Blurry background)

SHORTER Focal Length (Smaller Zoom) –> Deep DOF (Clear background)

Let look at the below photo:

Here the different of each Aperture size.

Beginner might wonder why the number grow smaller when the aperture is bigger. This is explain previously, just remember to golden rule, the smaller the F number is, the bigger the aperture size.

Let come back to the photo. The main focus point of the photo is the front statute face. Notice that when the smaller the aperture (bigger F number), the statute face at the back became clearer. Or the other way, the bigger the aperture, the harder you can see all the statute face but only 1 in focus.

Usage of Aperture & DOF

Please bear in mind that DSLR have better chance on creating very shallow DOF due to the sensor size (amount light received) and the vast range of lenses they have. By using long focal length and big aperture size lenses (300mm F2.8),  you can easily produce very blurry background that can’t be achieved by normal Digital Camera.

Fear not! That doesn’t mean your normal Digital Camera can’t have shallow DOF. You can try this few method to achieved shallow DOF at normal Digital Camera.

- Turn on the MACRO mode of your camera. The MACRO mode have a little flower icon.

- Zoom in as much as possible. (Use maximum zoom)

- Place the object as near as possible to your camera.

For LX3, thanks to the superb bright lens (F2.0), is quite easy to create a shallow DOF with it. Here is some simple guide.

- Turn the Dial to A mode (Aperture Priority), Set the F number to 2.0-2.8 (Big Aperture size).

- Make sure the Auto Focus dial is set to Macro mode (flower)

- Change the Focus setting to use Spot Focus/Central Focus. (Use the focus button to focus  the correct object you want to be in focus)

- Max up the zoom and Aperture (60mm F2.8) and ensure there is a distance between object and background.

When will you using the Shallow DOF and Deep DOF?

There wasn’t a rule for this. Normally, you will use a Deep DOF for scenery shot to make sure the whole scenery is sharp and clear, and use Shallow DOF for portrait shot to highlight the person you are taking.

Here is some example of application of different DOF.